1. Field of the Invention
In both research and medical diagnosis, there is a frequent need for the ability to determine regional plasma flows, as well as to image flow to specific organs. These two needs share certain requirements for markers capable of fulfilling these functions. The material should be removed from plasma during a single transorgan passage; should be well retained by virtue of a large volume of distribution or large number of receptor sites; and should provide for detectable radioemission.
There is a continuing need for compounds which can serve as indicators of blood flow and provide for imaging of specific organs.
2. Description of the Prior Art
Prior methods of regional blood flow used ceramic or plastic microspheres (which dwell permanently in the tissue and are not suitable for human study) or albumin microspheres (which are not satisfactory) or molecules such as antipyrine or thallium which are either not well retained or are poorly extracted.
Little and Bassingthwaighte, Intraorgan Regional Plasma Flows Using Highly Extracted Solute Desmethylimipramine. Fed. Proc. 42:580, 1983 (Abstract) reported the use of tritiated desmethylimipramine as a soluble indicator for regional plasma flow. A chlorinated imipramine has been reported in the literature. Tritiated desmethylimipramine is available from New England Nuclear No. NET593.